Process for Using Catalyst with Rapid Formation of Iron Sulfide in Slurry Hydrocracking

ABSTRACT

A process and apparatus is disclosed for converting heavy hydrocarbon feed into lighter hydrocarbon products. The heavy hydrocarbon feed is slurried with a catalyst comprising iron oxide and alumina to form a heavy hydrocarbon slurry and hydrocracked to produce lighter hydrocarbons. The iron oxide in the catalyst converts to catalytically active iron sulfide in the presence of hydrogen and sulfur.

BACKGROUND OF THE INVENTION

This invention relates to a process and apparatus for the treatment ofcrude oils and, more particularly, to the hydroconversion of heavyhydrocarbons in the presence of additives and catalysts to provideuseable products and further prepare feedstock for further refining.

As the reserves of conventional crude oils decline, heavy oils must beupgraded to meet world demands. In heavy oil upgrading, heaviermaterials are converted to lighter fractions and most of the sulfur,nitrogen and metals must be removed. Heavy oils include materials suchas petroleum crude oil, atmospheric tower bottoms products, vacuum towerbottoms products, heavy cycle oils, shale oils, coal derived liquids,crude oil residuum, topped crude oils and the heavy bituminous oilsextracted from oil sands. Of particular interest are the oils extractedfrom oil sands and which contain wide boiling range materials fromnaphthas through kerosene, gas oil, pitch, etc., and which contain alarge portion of material boiling above 524° C. These heavy hydrocarbonfeedstocks may be characterized by low reactivity in visbreaking, highcoking tendency, poor susceptibility to hydrocracking and difficultiesin distillation. Most residual oil feedstocks which are to be upgradedcontain some level of asphaltenes which are typically understood to beheptane insoluble compounds as determined by ASTM D3279 or ASTM D6560.Asphaltenes are high molecular weight compounds containing heteroatomswhich impart polarity.

Heavy oils must be upgraded in a primary upgrading unit before it can befurther processed into useable products. Primary upgrading units knownin the art include, but are not restricted to, coking processes, such asdelayed or fluidized coking, and hydrogen addition processes such asebullated bed or slurry hydrocracking (SHC). As an example, the yield ofliquid products, at room temperature, from the coking of some Canadianbitumens is typically about 55 to 60 wt-% with substantial amounts ofcoke as by-product. On similar feeds, ebullated bed hydrocrackingtypically produces liquid yields of 50 to 55 wt-%. U.S. Pat. No.5,755,955 describes a SHC process which has been found to provide liquidyields of 75 to 80 wt-% with much reduced coke formation through the useof additives.

In SHC, a three-phase mixture of heavy liquid oil feed cracks in thepresence of gaseous hydrogen over solid catalyst to produce lighterproducts under pressure at an elevated temperature. Iron sulfate hasbeen disclosed as an SHC catalyst, for example, in U.S. Pat. No.5,755,955. Iron sulfate monohydrate is typically ground down to smallersize for better dispersion and facilitation of mass transfer. Ironsulfate (FeSO₄) usually requires careful thermal treatment in air toremove water from iron sulfate which is typically provided in a hydratedform. Water can inhibit conversion of FeSO₄ to iron sulfide andtypically must be removed. It is thought that iron sulfate monohydratedecomposes slowly in an SHC to form iron sulfide. Drying the ironsulfate monohydrate in-situ initially dehydrates to FeSO₄ as shown inFormula (1). However, FeSO₄ also rehydrates to the monohydrate duringits decomposition to form iron sulfide in Formula (2). Ultimately, FeSO₄converts to iron sulfide as shown in Formula (3):

2Fe(SO₄).H₂O+8H₂→2Fe(SO₄)+2H₂O+8H₂  (1)

2Fe(SO₄)+2H₂O+8H₂→FeS+Fe(SO₄).H₂O+4H₂O+4H₂  (2)

FeS+Fe(SO₄).H₂O+4H₂O+4H₂→2FeS+10H₂O  (3)

Consequently, the amount of water in the system may limit the rate atwhich iron sulfide can form. Thermal treatment also removes volatilessuch as carbon dioxide to make the catalyst denser and opens up thepores in the catalyst to make it more active.

Iron sulfate already contains sulfur. The thermal treatment converts theiron in iron sulfate to catalytically active iron sulfide. The sulfurfrom iron sulfate contributes to the sulfur in the product that has tobe removed. Other iron containing catalysts such as limonite, whichcontains FeO(OH).nH₂O, require presulfide treatment for betterdispersion and conversion of the iron oxide to the active iron sulfideaccording to CA 2,426,374. Presulfide treatment adds sulfur to thecatalyst and consequently to the heavy hydrocarbon being processed. Assuch, extra sulfur must usually be removed from the product. The activeiron in the +2 oxidation state in the iron sulfide catalyst is requiredto obtain adequate conversion and selectivity to useful liquids and toavoid higher coke formation. U.S. Pat. No. 4,591,426 mentions bauxitewithout examining it and exemplifies limonite and laterite as catalysts.SHC catalysts are typically ground to a very small particle diameter tofacilitate dispersion and promote mass transfer.

During an SHC reaction, it is important to minimize coking. It has beenshown by the model of Pfeiffer and Saal, PHYS. CHEM. 44, 139 (1940),that asphaltenes are surrounded by a layer of resins, or polar aromaticswhich stabilize them in colloidal suspension. In the absence of polararomatics, or if polar aromatics are diluted by paraffinic molecules orare converted to lighter paraffinic and aromatic materials, theseasphaltenes can self-associate, or flocculate to form larger molecules,generate a mesophase and precipitate out of solution to form coke.

Toluene can be used as a solvent to dissolve to separate carbonaceoussolids from lighter hydrocarbons in the SHC product. The solids notdissolved by toluene include catalyst and toluene insoluble organicresidue (TIOR). TIOR includes coke and mesophase and is heavier and lesssoluble than asphaltenes which are soluble in heptane. Mesophaseformation is a critical reaction constraint in slurry hydrocrackingreactions. Mesophase is a semi-crystalline carbonaceous material definedas round, anisotropic particles present in pitch boiling above 524° C.The presence of mesophase can serve as a warning that operatingconditions are too severe in an SHC and that coke formation is likely tooccur under prevailing conditions.

SUMMARY OF THE INVENTION

We have found that iron oxide in the +3 oxidation state with aluminapresent rapidly converts to catalytically active iron sulfide in the +2oxidation state without the need of for presulfiding, preheating ordrying. The iron oxide converts to iron sulfide simply by heating theheavy hydrocarbon feed with hydrogen and iron oxide and alumina catalystto a temperature of no more than 410° C. The iron oxide efficientlyreacts with hydrogen sulfide provided by the reaction of sulfurcompounds in the feed with hydrogen. Typically, no sulfur must be addedto the hydrocarbon feed to activate the catalyst making for lesshydrogen required to react with the sulfur and less hydrogen sulfide tobe removed from the product. Additionally, we have found that the ironoxide and alumina catalyst can achieve greater than 400% increase in APIgravity.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, reference is made to theaccompanying drawings.

FIG. 1 is a schematic flow scheme for a SHC plant.

FIG. 2 is a plot of an XRD of a sample of TIOR with the peaks in thehydrocarbon region shaded.

FIG. 3 is a plot of an XRD of a sample of TIOR with the non-mesophasepeaks shaded in the hydrocarbon region.

FIG. 4 is a series of XRD plots for TIOR made with iron sulfatecatalyst.

FIG. 5 is a series of XRD plots for TIOR made with the catalyst of thepresent invention.

FIG. 6 is an XRD plot for TIOR made with iron sulfide monohydratecatalyst.

FIG. 7 is a SEM micrograph of iron sulfide monohydrate catalyst.

FIG. 8 is an XRD plot for TIOR made with limonite catalyst.

FIG. 9 is a SEM micrograph of limonite catalyst.

FIG. 10 is an XRD plot for TIOR made with bauxite catalyst.

FIG. 11 is a STEM micrograph of bauxite catalyst.

FIG. 12 is a PLM micrograph of TIOR made with iron sulfide monohydratecatalyst.

FIG. 13 is a PLM micrograph of TIOR made with limonite catalyst.

FIG. 14 is a PLM micrograph of TIOR made with bauxite catalyst.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The process and apparatus of this invention is capable of processing awide range of heavy hydrocarbon feedstocks. It can process aromaticfeedstocks, as well as feedstocks which have traditionally been verydifficult to hydroprocess, e.g. vacuum bottoms, visbroken vacuumresidue, deasphalted bottom materials, off-specification asphalt,sediment from the bottom of oil storage tanks, etc. Suitable feedsinclude atmospheric residue boiling at about 650° F. (343° C.), heavyvacuum gas oil (VGO) and vacuum residue boiling at about 800° F. (426°C.) and vacuum residue boiling above about 950° F. (510° C.). Throughoutthis specification, the boiling temperatures are understood to be theatmospheric equivalent boiling point (AEBP) as calculated from theobserved boiling temperature and the distillation pressure, for exampleusing the equations furnished in ASTM D1160. Furthermore, the term“pitch” is understood to refer vacuum residue, or material having anAEBP of greater than about 975° F. (524° C.). Feeds of which 90 wt-%boils at a temperature greater than or equal to 572° F. (300° C.) willbe suitable. Suitable feeds include an API gravity of no more than 20degrees, typically no more than 10 degrees and may include feeds withless than 5 degrees.

In the exemplary SHC process as shown in FIG. 1, one, two or all of aheavy hydrocarbon oil feed in line 8, a recycle pitch stream containingcatalyst particles in line 39, and recycled heavy VGO in line 37 may becombined in line 10. The combined feed in line 10 is heated in theheater 32 and pumped through an inlet line 12 into an inlet in thebottom of the tubular SHC reactor 13. Solid particulate catalystmaterial may be added directly to heavy hydrocarbon oil feed in the SHCreactor 13 from line 6 or may be mixed from line 6′ with a heavyhydrocarbon oil feed in line 12 before entering the reactor 13 to form aslurry in the reactor 13. It is not necessary and may be disadvantageousto add the catalyst upstream of the heater 32. It is possible that inthe heater, iron particles may sinter or agglomerate to make larger ironparticles, which is to be avoided. Many mixing and pumping arrangementsmay be suitable. It is also contemplated that feed streams may be addedseparately to the SHC reactor 13. Recycled hydrogen and make up hydrogenfrom line 30 are fed into the SHC reactor 13 through line 14 afterundergoing heating in heater 31. The hydrogen in line 14 that is notpremixed with feed may be added at a location above the feed entry inline 12. Both feed from line 12 and hydrogen in line 14 may bedistributed in the SHC reactor 13 with an appropriate distributor.Additionally, hydrogen may be added to the feed in line 10 before it isheated in heater 32 and delivered to the SHC reactor in line 12.Preferably the recycled pitch stream in line 39 makes up in the range ofabout 5 to 15 wt-% of the feedstock to the SHC reactor 13, while theheavy VGO in line 37 makes up in the range of 5 to 50 wt-% of thefeedstock, depending upon the quality of the feedstock and theonce-through conversion level. The feed entering the SHC reactor 13comprises three phases, solid catalyst particles, liquid and solidhydrocarbon feed and gaseous hydrogen and vaporized hydrocarbon.

The process of this invention can be operated at quite moderatepressure, in the range of 500 to 3500 psi (3.5 to 24 MPa) and preferablyin the range o 1500 to 2500 psi (10.3 to 17.2 MPa), without cokeformation in the SHC reactor 13. The reactor temperature is typically inthe range of about 400 to about 500° C. with a temperature of about 440to about 465° C. being suitable and a range of 445 to 460° C. beingpreferred. The LHSV is typically below about 4 h⁻¹ on a fresh feedbasis, with a range of about 0.1 to 3 h⁻¹ being preferred and a range ofabout 0.3 to 1 h⁻¹ being particularly preferred. Although SHC can becarried out in a variety of known reactors of either up or downflow, itis particularly well suited to a tubular reactor through which feed,catalyst and gas move upwardly. Hence, the outlet from SHC reactor 13 isabove the inlet. Although only one is shown in the FIG. 1, one or moreSHC reactors 13 may be utilized in parallel or in series. Because theliquid feed is converted to vaporous product, foaming tends to occur inthe SHC reactor 13. An antifoaming agent may also be added to the SHCreactor 13, preferably to the top thereof, to reduce the tendency togenerate foam. Suitable antifoaming agents include silicones asdisclosed in U.S. Pat. No. 4,969,988.

A gas-liquid mixture is withdrawn from the top of the SHC reactor 13through line 15 and separated preferably in a hot, high-pressureseparator 20 kept at a separation temperature between about 200 and 470°C. (392 and 878° F.) and preferably at about the pressure of the SHCreactor. In the hot separator 20, the effluent from the SHC reactor 13is separated into a gaseous stream 18 and a liquid stream 16. The liquidstream 16 contains heavy VGO. The gaseous stream 18 comprises betweenabout 35 and 80 vol-% of the hydrocarbon product from the SHC reactor 13and is further processed to recover hydrocarbons and hydrogen forrecycle.

A liquid portion of the product from the hot separator 20 may be used toform the recycle stream to the SHC reactor 13 after separation which mayoccur in a liquid vacuum fractionation column 24. Line 16 introduces theliquid fraction from the hot high pressure separator 20 preferably to avacuum distillation column 24 maintained at a pressure between about0.25 and 1.5 psi (1.7 and 10.0 kPa) and at a vacuum distillationtemperature resulting in an atmospheric equivalent cut point betweenlight VGO and heavy VGO of between about 250° and 500° C. (4820 and 932°F.). Three fractions may be separated in the liquid fractionationcolumn: an overhead fraction of light VGO in an overhead line 38 whichmay be further processed, a heavy VGO stream from a side cut in line 29and a pitch stream obtained in a bottoms line 40 which typically boilsabove 450° C. At least a portion of this pitch stream may be recycledback in line 39 to form part of the feed slurry to the SHC reactor 13.Remaining catalyst particles from SHC reactor 13 will be present in thepitch stream and may be conveniently recycled back to the SHC reactor13. Any remaining portion of the pitch stream is recovered in line 41.During the SHC reaction, it is important to minimize coking. Adding alower polarity aromatic oil to the feedstock reduces coke production.The polar aromatic material may come from a wide variety of sources. Aportion of the heavy VGO in line 29 may be recycled by line 37 for formpart of the feed slurry to the SHC reactor 13. The remaining portion ofthe heavy VGO may be recovered in line 35.

The gaseous stream in line 18 typically contains lower concentrations ofaromatic components than the liquid fraction in line 16 and may be inneed of further refining. The gaseous stream in line 18 may be passed toa catalytic hydrotreating reactor 44 having a bed charged withhydrotreating catalyst. If necessary, additional hydrogen may be addedto the stream in line 18. Suitable hydrotreating catalysts for use inthe present invention are any known conventional hydrotreating catalystsand include those which are comprised of at least one Group VIII metaland at least one Group VI metal on a high surface area support material,such as a refractory oxide. The gaseous stream is contacted with thehydrotreating catalyst at a temperature between about 200° and 600° C.(430° and 1112° F.) in the presence of hydrogen at a pressure betweenabout 5.4 and 34.5 MPa (800 and 5000 psia). The hydrotreated productfrom the hydrotreating reactor 44 may be withdrawn through line 46.

The effluent from the hydrotreating reactor 44 in line 46 may bedelivered to a cool high pressure separator 19. Within the coolseparator 19, the product is separated into a gaseous stream rich inhydrogen which is drawn off through the overhead in line 22 and a liquidhydrocarbon product which is drawn off the bottom through line 28. Thehydrogen-rich stream 22 may be passed through a packed scrubbing tower23 where it is scrubbed by means of a scrubbing liquid in line 25 toremove hydrogen sulfide and ammonia. The spent scrubbing liquid in line27 may be regenerated and recycled and is usually an amine. The scrubbedhydrogen-rich stream emerges from the scrubber via line 34 and iscombined with fresh make-up hydrogen added through line 33 and recycledthrough a recycle gas compressor 36 and line 30 back to reactor 13. Thebottoms line 28 may carry liquid hydrotreated product to a productfractionator 26.

The product fractionator 26 may comprise one or several vessels althoughit is shown only as one in FIG. 1. The product fractionator produces aC₄— recovered in overhead line 52, a naphtha product stream in line 54,a diesel stream in line 56 and a light VGO stream in bottoms line 58.

We have discovered that catalyst particles comprising between about 2and about 45 wt-% iron oxide and between about 20 and about 90 wt-%alumina make excellent SHC catalysts. Iron-containing bauxite is apreferred bulk available mineral having these proportions. Bauxitetypically has about 10 to about 40 wt-% iron oxide, Fe₂O₃, and about 54to about 84 wt-% alumina and may have about 10 to about 35 wt-% ironoxide and about 55 to about 80 wt-% alumina. Bauxite also may comprisesilica, SiO₂, and titania, TiO2, in aggregate amounts of usually no morethan 10 wt-% and typically in aggregate amounts of no more than 6 wt-%.Iron is present in bauxite as iron oxide and aluminum is present inbauxite as alumina. Volatiles such as water and carbon dioxide are alsopresent in bulk available minerals, but the foregoing weight proportionsexclude the volatiles. Iron oxide is also present in bauxite in ahydrated form, Fe₂O₃.nH₂O. Again, the foregoing proportions exclude thewater in the hydrated composition.

Bauxite can be mined and ground to particles having a mean particlediameter of 0.1 to 5 microns. The particle diameter is the length of thelargest orthogonal axis through the particle. We have found that aluminaand iron oxide catalysts with mean particle diameters of no less than200 microns, using the dry method to determine particle diameter,exhibit performance comparable to the performance of the same catalystground down to the 0.1 to 5 micron range. Hence, alumina and iron oxidecatalysts with mean particle diameters of no less than 200 microns,suitably no less than 249 microns and preferably no less than 250microns can be use to promote SHC reactions. In an embodiment thecatalyst should not exceed about 600 microns and preferably will notexceed about 554 microns in terms of mean particle diameter using thedry method to determine particle diameter. Mean particle diameter is theaverage particle diameter of all the catalyst particles fed to thereactor which may be determined by a representative sampling.Consequently, less effort must be expended to grind the catalystparticles to smaller diameters for promoting SHC, substantially reducingtime and expense. Particle size determinations were made using a drymethod which more closely replicates how the bulk catalyst willinitially encounter hydrocarbon feed. A wet method for determiningparticle diameters appeared to break particles of bauxite into smallerparticles which may indicate what occurs upon introduction of catalystinto an SHC reactor.

The alumina in the catalyst can be in several forms including alpha,gamma, theta, boehmite, pseudo-boehmite, gibbsite, diaspore, bayerite,nordstrandite and corundum. Alumina can be provided in the catalyst byderivatives such as spinels and perovskites. Suitable bauxite isavailable from Saint-Gobain Norpro in Stow, Ohio who may provide it airdried and ground, but these treatments may not be necessary for suitableperformance as a catalyst for SHC.

We have found that these alumina and iron oxide containing catalystparticles are more effective if they are not first subjected to athermal treatment or a sulfide treatment. We have also found that waterdoes not impede formation of active iron sulfide from iron oxide inbauxite, so it is not required to remove water by the thermal or anyother drying treatment. The water on the catalyst can be eitherchemically bound to the iron oxide, alumina or other components of thecatalyst or be physically bound to the catalyst. More than 23 wt-% watercan be present on the catalyst without affecting the performance of thecatalyst. We have found that about 39 wt-% water does not affectperformance of the catalyst and would expect up to at least about 40wt-% water on the catalyst would not affect performance. Water oncatalyst can be determined by loss on ignition (LOI), which involvesheating the catalyst to elevated temperature such as 900° C. Allvolatiles come off in addition to water but the non-water volatiles werenot significant.

The iron in iron oxide in the presence of alumina such as in bauxitequickly converts to active iron sulfide without the need for presentingexcess sulfur to the catalyst in the presence of heavy hydrocarbon feedand hydrogen at high temperature as required for other SHC catalystsbefore addition to the reaction zone. The iron sulfide has severalmolecular forms, so is generally represented by the formula, Fe_(x)S,where x is between 0.7 and 1.3. We have found that essentially all ofthe iron oxide converts to iron sulfide upon heating the mixture ofhydrocarbon and catalyst to 410° C. in the presence of hydrogen andsulfur. In this context, “essentially all” means no peak for iron oxideis generated on an XRD plot of intensity vs. two theta degrees at 33.1two theta degrees or no less than 99 wt-% conversion to iron sulfide.Sulfur may be present in the hydrocarbon feed as organic sulfurcompounds. Consequently, the iron in the catalyst may be added to theheavy hydrocarbon feed in the +3 oxidation state, preferably as Fe₂O₃.The catalyst may be added to the feed in the reaction zone or prior toentry into the reaction zone without pretreatment. After mixing the ironoxide and alumina catalyst with the heavy hydrocarbon feed whichcomprises organic sulfur compounds and heating the mixture to reactiontemperature, organic sulfur compounds in the feed convert to hydrogensulfide and sulfur-free hydrocarbons. The iron in the +3 oxidation statein the catalyst quickly reacts at reaction temperature with hydrogensulfide produced in the reaction zone by the reaction of organic sulfurand hydrogen. The reaction of iron oxide and hydrogen sulfide produceiron sulfide which is the active form of the catalyst. Iron is thenpresent in the +2 oxidation state in the reactor. The efficiency ofconversion of iron oxide to iron sulfide enables operation withoutadding sulfur to the feed if sufficient available sulfur is present inthe feed to ensure complete conversion to iron sulfide. Otherwise,sulfur may be added for low sulfur feeds if necessary to convert all theiron oxide to iron sulfide. Because the iron oxide and alumina catalystis so efficient in converting iron oxide to iron sulfide and inpromoting the SHC reaction, less iron must be added to the SHC reactor.Consequently, less sulfur is required to convert the iron oxide to ironsulfide minimizing the need for sulfur addition. The iron oxide andalumina catalyst does not have to be subjected to elevated temperaturein the presence of hydrogen to obtain conversion to iron sulfide.Conversion occurs at below SHC reaction temperature. By avoiding thermaland sulfiding pretreatments, process simplification and material costreduction are achieved. Additionally, less hydrogen is required and lesshydrogen sulfide and other sulfur must be removed from the SHC product.

Several terms are noteworthy in the characterization of performance ofthe iron oxide and alumina catalysts in SHC. “Iron content” is theweight ratio of iron on the catalyst relative to the non-gas materialsin the SHC reactor. The non-gas materials in the reactor are typicallythe hydrocarbon liquids and solids and the catalyst and do not includereactor and ancillary equipment. “Aluminum content” is the weight ratioof aluminum relative to the non-gas materials in the in the SHC reactor.“Pitch conversion” is the weight ratio of material boiling at or below524° C. in the product relative to the material boiling above 524° C. inthe feed. “C₅-524° C. yield” is the weight ratio of material in theproduct boiling in the C₅ boiling range to 524° C. relative to the totalhydrocarbon feed. “TIOR” is the toluene-insoluble organic residue whichrepresents non-catalytic solids in the product part boiling over 524° C.“Mesophase” is a component of TIOR that signifies the existence of coke,another component of TIOR. “API gravity index” is a parameter thatrepresents the flowability of the material. Mean particle or crystallitediameter is understood to mean the same as the average particle orcrystallite diameter and includes all of the particles or crystallitesin the sample, respectively.

Iron content of catalyst in an SHC reactor is typically about 0.1 toabout 4.0 wt-% and usually no more than 2.0 wt-% of the catalyst andliquid in the SHC. Because the iron in the presence of alumina, such asin bauxite, is very effective in quickly producing iron sulfidecrystallites from the sulfur in the hydrocarbon feed, less iron on theiron oxide and alumina catalyst is necessary to promote adequateconversion of heavy hydrocarbon feed in the SHC reactor. The ironcontent of catalyst in the reactor may be effective at concentrationsbelow or at about 1.57 wt-%, suitably no more than about 1 wt-%, andpreferably no more than about 0.7 wt-% relative to the non-gas materialin the reactor. In an embodiment, the iron content of catalyst in thereactor should be at least about 0.4 wt-%. Other bulk available mineralsthat contain iron were not able to perform as well as iron oxide andalumina catalyst in the form of bauxite in terms of pitch conversion,C₅-524° C. yield, TIOR yield and mesophase yield. At 2 wt-% iron,limonite was comparable to bauxite only after being subjected toextensive pretreatment with sulfide, after which the limonite producedtoo much mesophase yield. At the low concentration of 0.7 wt-% iron onthe catalyst in the reactor, no catalyst tested performed as well asiron oxide and alumina catalyst while suppressing TIOR and mesophaseyield. At around 1 and 1.5 wt-% iron content in the reactor, bauxiteperformed better than iron sulfate monohydrate and limonite. We havefurther found that the resulting product catalyzed by the iron oxide andalumina catalyst can achieve an API gravity of at least four times thatof the feed, as much as six times that of the feed and over 24 timesthat of the feed indicating excellent conversion of heavy hydrocarbons.Use of iron oxide an alumina catalyst like bauxite allows superiorconversion of heavy hydrocarbon feed to desirable products with lesscatalyst and trace or no generation of mesophase which signifies cokegeneration.

The presence of alumina on the iron containing catalyst has a beneficialeffect on performance. Alumina combined with other iron containingcatalyst improves performance in a SHC reaction, particularly in thesuppression of mesophase production. Naturally occurring bauxite hasbetter performance than other iron and aluminum containing catalysts. Asuitable aluminum content on the catalyst is about 0.1 to about 20 wt-%relative to non-gas solids in the reactor. An aluminum content of nomore than 10 wt-% may be preferred.

The crystallites of iron sulfide generated by bauxite in the reactor atreaction conditions have diameters across the crystallite in the in thenanometer range. An iron sulfide crystal is a solid in which theconstituent iron sulfide molecules are packed in a regularly ordered,repeating pattern extending in all three spatial dimensions. An ironsulfide crystalliteis a domain of solid-state matter that has the samestructure as a single iron sulfide crystal. Nanometer-sized iron sulfidecrystallites disperse well over the catalyst and disperse well in thereaction liquid. The iron sulfide crystallites are typically about thesame size as the iron sulfide precursor crystallites from which they areproduced. In bauxite, the iron sulfide precursor crystallite is ironoxide. By not thermally treating the bauxite, iron oxide crystals do notsinter together and become larger. Consequently, the catalyticallyactive iron sulfide crystallites produced from the iron oxide remain inthe nanometer range. The iron sulfide crystallites may have an averagelargest diameter between about 1 and about 150 nm, typically no morethan about 100 nm, suitably no more than about 75 nm, preferably no morethan about 50 nm, more preferably no more than about 40 nm as determinedby electron microscopy. The iron sulfide crystallites suitably have amean crystallite diameter of no less than about 5 nm, preferably no lessthan about 10 nm and most preferably no less than about 15 nm asdetermined by electron microscopy. Electron microscopy reveals that theiron sulfide crystallites are fairly uniform in diameter, well dispersedand predominantly present as single crystals. Use of XRD to determineiron sulfide crystallite size yields smaller crystallite sizes which isperhaps due to varying iron to sulfur atomic ratios present in the ironsulfide providing peaks near the same two theta degrees. XRD revealsiron sulfide crystallite mean diameters of between about 1 and about 25nm, preferably between about 5 and about 15 nm and most preferablybetween about 9 and about 12 nm. Upon conversion of the iron oxide toiron sulfide, for example, in the reactor, a composition of mattercomprising about 2 to about 45 wt-% iron sulfide and about 20 to about98 wt-% alumina is generated and dispersed in the heavy hydrocarbonmedium to provide a slurry. The composition of matter has iron sulfidecrystallites in the nanometer range as just described. We have foundthat the iron oxide precursor crystallites in bauxite have about thesame particle diameter as the iron sulfide crystallites formed fromreaction with sulfur. We have further found that the alumina and ironoxide catalyst can be recycled to the SHC reactor at least twice withoutiron sulfide crystallites becoming larger.

Cross polarized light microscopy (PLM) may be used to identify themesophase structure and quantify mesophase concentration in TIOR fromSHC reactions using ASTM D 4616-95. The semi-crystalline nature ofmesophase makes it optically active under cross polarized light. TIORsamples are collected, embedded in epoxy and polished. The relativeamounts of mesophase can be quantified using PLM to generate an imagefrom the sample and identifying and counting mesophase in the PLM image.

We have also found that this semi-crystalline nature of mesophase alsoallows it to appear in an XRD pattern. We have found that the presenceof mesophase is indicated by a peak at 26 two theta degrees, within±0.3° and preferably within ±0.2° in an XRD pattern. This mesophase peakfound in XRD images correlates with the mesophase found by PLM. We havefound the broad feature in the range between about 20 and 29.5 two thetadegrees can be associated with mesophase.

To analyze a sample for mesophase, a sample of hydrocarbon material isblended with a solvent such as toluene, centrifuged and the liquid phasedecanted. These steps can be repeated. The solids may then be dried in avacuum oven such as at 90° C. for 2 hours. At this point the driedsample is ready for mesophase identification either by PLM or by XRD.For XRD, a standard such as silicon is worked into the solids samplealong with a solvent such as acetone to form a slurry to enable mixingthe standard with the sample. The solvent should quickly evaporateleaving the sample with a predetermined concentration of standard.Approximately 1 gram of sample with standard is spread onto a XRD sampleholder and placed into the XRD instrument such as a Scintag XDS-2000 XRDinstrument and scanned using predetermined range parameters. Scan rangeparameters such as 2.0/70.0/0.02/0.6(sec) and 2.0/70.0/0.04/10(sec) aresuitable. Other parameters may be suitable. The resulting data isplotted, for example, by using JADE software from Materials Data, Inc.in Livermore, Calif., which may be loaded on the XRD instrument. TheJADE software uses International Center for Diffraction Data (ICDD) as adatabase of standards for phase identification and automatedsearch-match functions.

To calculate the mesophase concentration, the aggregate area of thepeaks in the total carbon region from 20° 2-theta degrees to the rightmost edge of a silicon peak at 28.5° two theta degrees should becalculated. The right most edge of the silicon peak is at about 29.5 twotheta degrees. If a standard other than silicon is used, the totalcarbon region should be calculated to include up to 29.5 two thetadegrees. Parts of the broad feature of a mesophase peak may lie in thistotal carbon region. In the JADE software, the Peak Paint function canbe used to obtain the peak area for the total carbon region from an XRDpattern. The total carbon region contains a mesophase peak at 26° twotheta degrees if mesophase is present and a silicon peak at 28.5° twotheta from a silicon standard added to the sample. Once the aggregatearea of the peaks in the total carbon region is determined, thenon-mesophase peaks in the total carbon region may be identified andtheir total area along with the area of the silicon peak calculated andsubtracted from the aggregate area of the peaks in the total carbonregion peak to provide the area of the mesophase peak. The non-mesophasepeaks in the total carbon region can be identified using the JADEsoftware which matches peak patterns in the plot to standard peakpatterns in the ICDD database. Bauxite, for example, typically includestitania which provides a peak at 26.2 two theta degrees. Othernon-mesophase may be identified to subtract the corresponding peak areafrom the mesophase peak area. The base line of the non-mesophase peakcan be approximated by drawing a base line connecting the base of eachside of the peak and demark it from the mesophase peak. Thesenon-mesophase peaks in the total carbon region and the silicon peak arehighlighted using the Peak Paint feature in the JADE software and theirarea calculated. The non-mesophase peaks are not typically significantrelative to the area of the mesophase peak. The two areas for themesophase peak and the silicon peak can then be used to calculate theproportional mesophase weight fraction in the sample by use of Formula(1):

X _(m) =X _(st)(A _(m) /A _(st))  (1)

where X_(m) is the proportional mesophase weight fraction in a sample,X_(st) is the weight fraction of standard added to the sample such assilicon, Am is the mesophase peak area and A_(st) is the peak area ofthe standard. The term “proportional mesophase weight fraction” is usedbecause a correction factor accounting for the relationship between thestandard and the mesophase peaks may be useful in Formula (1), but we donot expect the correction factor to significantly change the result inFormula (1). The mesophase yield fraction which is the mesophaseproduced per hydrocarbon fed to the SHC reactor by weight should becalculated to determine whether the mesophase produced in the reactionis too high thereby indicating the risk of too much coke production. Theyield fraction of TIOR produced in a reaction per hydrocarbon feed byweight is calculated by Formula (2):

Y _(TIOR) =M _(TIOR) /M _(HCBN)  (2)

where Y_(TIOR) is the yield fraction of TIOR in the product; M_(TIOR) isthe yield mass of TIOR in the product and M_(HCBN) is the mass ofhydrocarbon in the feed. Masses can be used in the calculation as massflow rates in a continuous reaction or static masses in a batchreaction. The mesophase yield fraction is calculated by Formula (3):

Y _(mesophase) =X _(m) *Y _(TIOR)  (3)

where Y_(mesophase) is the mesophase yield fraction. These formulasenable calculation of the yield fraction of TIOR, Y_(TIOR), which ismass of TIOR produced per mass of hydrocarbon fed to the SHC reactorwhich can be multiplied by the fraction of mesophase in the TIOR sample,X_(m), to determine the yield fraction of mesophase, Y_(mesophase),which is mass of mesophase produced per mass of hydrocarbon fed to theSHC reactor. If the yield fraction of mesophase exceeds 0.5 wt-%, theseverity of an SHC reactor should be reduced to avoid excessive cokingin the reactor because mesophase production is substantial. In otherembodiments, severity should be moderated should the yield fraction ofmesophase exceed as little as 0.3 and as high as 0.8 wt-%.

The amount of mesophase determined by the optical PLM method of ASTM D4616-95 is a method that samples a two dimensional area which is avolume fraction. The XRD method samples a three dimensional volume andshould give a more accurate indication of mesophase in terms of weightfraction relative to feed. It would not be expected for the two methodsto give the identical result, but they should correlate.

Example 1

A feed suitable for SHC is characterized in Table I. Unless otherwiseindicated, this feed was used in all the Examples.

TABLE I Vacuum Bottoms Test (975° F.+) Specific Gravity, g/cc 1.03750API gravity −0.7 ICP Metals Ni, wt. ppm 143 V, wt. ppm 383 Fe, wt. ppm68.8 Microcarbon residue, wt-% 25.5 C, wt-% 80.3 H, wt-% 9.0 N, wt-% 0.4Total N, wt. ppm 5744 Oxygen, wt-% in organics 0.78 Sulfur, wt-% 7 Ash,wt-% 0.105 Heptane insolubles, wt-% 16.1 Pentane insolubles, wt-% 24.9Total chloride, mass ppm 124 Saybolt viscosity, Cst 150° C. 1400 Sayboltviscosity, Cst 177° C. 410

“ICP” stands for Inductively Coupled Plasma Atomic EmissionsSpectroscopy, which is a method for determining metals content.

Example 2

A TIOR sample from an SHC reaction using heavy oil feed from Example 1and 0.7 wt-% iron content on iron sulfate monohydrate catalyst as apercentage of non-gaseous materials in the SHC reactor was analyzed formesophase using an XRD method. A sample of SHC product material wasblended with toluene, centrifuged and the liquid phase decanted. Thesesteps were repeated on the remaining solids. The solids remaining werethen dried in a vacuum oven at 90° C. for 2 hours. Silicon standard wasadded to the sample to give a concentration of 5.3 wt-% by addingsilicon solid and acetone solvent to a sample of TIOR and slurriedtogether with a mortar and pestle. The acetone evaporated out of theslurry to leave a solid comprising TIOR blended with silicon standard.An approximately 1 gram sample of the solid sample with blended standardwas spread onto a XRD sample holder and placed into the XRD instrumentand scanned using parameters of 2.0/70.0/0.04/10(sec). The XRDinstrument was a Scintag X1 instrument which is a fixed slit systemequipped with a theta-theta goniometer, a Peltier-cooled detector and acopper tube. The XRD instrument was run at settings of 45 kV and 35 mA.The resulting data was plotted using JADE software which was loaded onthe XRD instrument.

FIGS. 2 and 3 show an XRD plot of the resulting TIOR sample. A peak witha centroid at 26.0 2-theta degrees represents the existence ofmesophase. The aggregate area of the peaks in the total carbon regionfrom 20° 2-theta degrees to the right most edge of a silicon peak at28.5° two theta degrees as shown shaded in FIG. 2 was calculated to be253,010 area counts using the Peak Paint function of JADE software. Theright-most edge of the peak in the total carbon region was at about 29.5two theta degrees. The non-mesophase peaks in the total carbon regionare identified and shaded along with the silicon peak with a centroid at28.5 two theta degrees in FIG. 3 using the Peak Paint function. Bauxite,for example, typically includes titania which provides a peak at 26.2two theta degrees. Other non-mesophase peaks are identified as such andhighlighted in FIG. 3. The base lines of the non-mesophase peaks areshown in FIG. 3 with base lines connecting the base of each side of therespective peak to demark it from the rest of the mesophase peak. Thesenon-mesophase peaks in the total carbon region and the silicon peak arehighlighted using the Peak Paint feature in the JADE software tocalculate their area. The area of the silicon peak is 43,190 areacounts, and the area other non-mesophase peaks in the total carbonregion is 1,374 area counts which is relatively insignificant. Theaggregate area of the peaks not associated with mesophase in thehydrocarbon range was calculated using Peak Paint to be 44,564 areacounts. The non-mesophase area was subtracted from the aggregate area ofthe peaks in the total carbon region peak to provide an area of themesophase peak of 208,446 area counts. The two areas for the mesophasepeak and the silicon peak were then used to calculate the percentmesophase by Formula (1):

X _(m)=0.053*(208446/43190)=0.2558  (1).

To determine the yield fraction of TIOR, Formula (2) is used for which:

Y _(TIOR) =M _(TIOR) /M _(HCBN)=18.85 g TIOR/342 g HCBN=0.0551  (2).

Accordingly, Formula (3) is used to determine the yield fraction ofmesophase:

Y _(mesophase) =X _(m) *Y _(TIOR)=0.249*0.0551=0.0141  (3).

The Y_(mesophase) expressed as a percentage of 1.41 wt-% correlates tothe mesophase concentration of 1.22% determined by PLM using ASTM D4616-95. Since the mesophase yield fraction is substantial in that it isabove 0.5 wt-% the reaction was in danger of excessive coking whichshould prompt moderating its severity.

Example 3

In this example, we examined the ability of iron in iron sulfatemonohydrate to convert to the active iron sulfide. Iron sulfatemonohydrate was mixed with vacuum resid of Example 1 at 450° C. and 2000psi (137.9 bar) in an amount such that 2 wt-% iron was present relativeto the non-gaseous materials in the reactor. The temperature was chosenbecause it is the optimal temperature for pitch conversion for sulfurmonohydrate catalyst. The semi-continuous reaction was set up so thathydrocarbon liquid and catalyst remained in the reactor; whereas, 6.5standard liters/minute (sl/m) of hydrogen were fed through the reactionslurry and vented from the reactor. X-ray diffraction (XRD)characterization of solid material separated from vacuum resid feedduring different stages of the reaction shows that the transformation ofFe(SO₄).H₂O to FeS is comparatively slow. FIG. 4 shows XRD patterns fromsamples taken from the semi-continuous reaction at various timeintervals. FIG. 4 shows intensity versus two theta degrees for four XRDpatterns taken at 0, 15, 30, 60 and 80 minutes going from highest tolowest patterns in FIG. 4. Time measurement began after the reactor washeated for 30 minutes to reaction conditions. The presence ofFe(SO₄).H₂O is indicated in the XRD pattern by a peak at 18.3 and 25.9two theta degrees. Table II below gives the proportion of Fe(SO₄).H₂O attime. After reactor heat up at 0 minutes, only about 30 wt-% of the Feis present as iron sulfide shown by a peak at 44 two theta degrees. Onlyafter 80 minutes is most of the Fe(SO₄).H₂O converted to FeS.

TABLE II Reaction Time (minutes) Fe(SO₄)•H₂O (wt-%) 0 70 15 16 30 14 605 80 4

Example 4

In order to understand the formation of iron sulfide from bauxite anexperiment was performed by charging vacuum resid of Example 1 to thesemi-continuous reactor at 460° C., 2000 psi (137.9 bar), and feedinghydrogen through the resid at 6.5 sl/m. The bauxite catalyst was presentin an amount such that 0.7 wt-% iron was in the reactor relative to thehydrocarbon liquid and catalyst. The reaction was run for 80 minutesafter the reactor was preliminarily heated for 30 minutes. XRD patternswere taken of solids collected from the reaction at 0, 15 and 80 minutesafter preliminary heat up. A second set of experiments were performedwith the same reaction conditions, except the reactor temperature wasset at 410° C. and solids were collected at 0 and 80 minutes afterpreliminary heat up. The XRD patterns are shown in FIG. 5. Theexperiments conducted at 460° C. are the lowest three XRD patterns inFIG. 5, and the experiments conducted at 410° C. are the highest threeXRD patterns in FIG. 5. In all cases, iron sulfide had already formed bythe time the reactor reached both reaction temperatures indicated by thepeak at 44 two theta degrees. No evidence of iron oxide is present inany of the XRD patterns indicating that essentially all of the ironoxide had converted to iron sulfide.

Example 5

Bauxite containing 17.7 wt-% Fe present as Fe₂O₃ and 32.9% wt-% Alpresent as boehmite alumina was compared with other bulk available,iron-containing minerals such as iron sulfate monohydrate and Yandilimonite ore from various sources. Particle size characterizations weredetermined using the wet method of ASTM UOP856-07. The characterizationdata for all of the materials are shown in Table III.

TABLE III Iron Sulfate mono- Limonite Sample Description Bauxite hydrateHematite Fines Al, wt-% 32.9 <0.006 0.7 Fe, wt-% 17.7 29.1 67.8 52.4 Ti,wt-% 1.88 <0.003 0.029 LOI at 900° C., mass-% 7.6 54.6 0.8 17.1 IronCompound Fe₂O₃ Fe(SO₄) Fe₂O₃ FeOOH Iron compound, wt-% 25.3 79.1 97.083.4 SiO₂ 4.5 Al₂O₃ 62.2 1.3 S 0.0 18.7 0.0 BET surface area, m²/g 159.05.0 94.0 LANG surface area, m²/g 276.0 162.0 pore volume, cc/g 0.2 0.00.1 pore diameter, A 53.0 104.0 41.0 Particle size median diameter, μ1.2 2.9 3.8 2.8 Mean diameter, μ 1.0 2.3 2.7 26.7 <10μ 0.5 1.1 1.3 0.3<25μ 0.7 1.8 2.4 0.9 <50μ 1.2 2.9 3.8 2.8 <75μ 1.9 4.1 5.3 26.9 <90μ 2.85.5 6.9 91.1

In a typical experiment, 334 grams of vacuum resid of Example 1 wascombined in a 1 liter autoclave with one of the iron sources, adding theiron at between 0.4 and 2 wt-%. In the examples cited in Table IV, theautoclave was heated to 445° C. for 80 minutes at 2000 psi (137.9 bar).Hydrogen was continuously added through a sparger and passed through thereactor at a rate of 6.5 standard liters per minute and removed througha back pressure valve to maintain pressure. The hydrogen stripped outthe light products which were condensed in cooled knock-out trap pots.Some of the limonite catalysts were pretreated by adding 1 or 2 wt-%sulfur relative to the feed and catalyst and heating the mixture to 320°or 350° C. at 2000 psi (137.9 bar) over hydrogen for an hour to activatethe catalyst before heating the mixture to reaction temperature.

In Table IV, “mesophase yield, XRD, wt-% indicates mesophase identifiedby XRD and is expressed relative to the total hydrocarbon feed.“Mesophase optical” is a percentage of mesophase identified in a sampleexamined by polarized light microscopy. All of the yield numbers arecalculated as a ratio to the feed.

TABLE IV Bauxite Iron sulfate monohydrate Run 522- 522- 522- 522- 522-522- 522- 522- 522- 522- 522- Sample Description 12 13 125 124 82 87 84523-4 132 81 41 65 Pretreatment no no no no No no no no no no no no Ironcontent, wt-% 0.4 0.5 0.7 0.7 1.0 1.5 2.0 0.7 0.7 1.0 1.5 2.0Temperature, ° C. 445 445 445 445 445 445 445 450 445 445 445 445 Pitchconversion, 82.3 82.1 82.0 83.1 82.6 82.5 83.4 76.88 78.4 79.1 81.8 80.0wt-% H₂S, CO & CO₂ yield, wt-% 4.6 4.7 4.6 4.5 4.1 3.4 3.4 4.6 4.4 3.94.5 4.2 C₁-C₄ yield, wt-% 9.8 9.8 9.3 9.2 9.2 8.8 7.5 11.6 10.9 9.9 11.39.7 Naphtha (C₅-204° C.) yield, wt-% 24.9 21.0 22.9 22.5 20.8 19.2 19.821.1 24.9 22.7 22.3 20.4 LVGO (204° C.-343° C.) yield, 24.9 25.0 24.924.6 27.4 25.2 29.6 25.8 22.8 24.9 23.9 27.3 wt-% HVGO (343° C.-524° C.)yield, 21.7 21.6 21.8 21.9 22.2 24.4 22.4 13.1 15.2 17.1 15.5 15.3 wt-%Pitch (524° C.+) yield, wt-% 16.0 16.2 16.1 15.1 15.5 15.8 15.0 20.619.3 19.0 16.5 18.0 C₅-524° C. yield, wt-% 71.4 67.5 69.6 69.0 70.4 68.871.8 60.0 62.9 64.8 61.7 63.1 TIOR yield, wt-% 3.0 2.5 2.3 2.3 2.9 2.61.9 7.1 7.1 6.1 4.0 3.0 Mesophase yield, XRD, wt-% 0.22 0.15 0.03 0.070.00 0.00 0.00 1.03 0.75 0.43 0.37 0.22 Mesophase, Optical, % 0.11 0.280.00 0.07 0.00 0.00 0.00 1.70 0.94 0.50 0.39 1.77 Hematite Limonite Run522- 522- Sample Description 122 74 522-86 522-73 522-77 Pretreatment nono 1% sulfur, 2% sulfur, 2% sulfur, 350° C. 320° C. 350° C. Ironcontent, wt-% 0.7 0.7 1.0 0.7 2.0 Temperature, ° C. 445 445 445 445 445Pitch conversion, 79.3 70.1 79.1 75.0 83.1 wt-% H₂S, CO & CO₂ yield,wt-% 4.2 3.8 4.3 4.4 5.8 C₁-C₄ yield, wt-% 10.4 11.4 9.7 10.3 10.5Naphtha (C₅-204° C.) yield, wt-% 25.1 1.5 22.6 1.2 21.5 LVGO (204°C.-343° C.) yield, 21.2 30.0 24.0 29.5 27.5 wt-% HVGO (343° C.-524° C.)yield, 16.3 30.1 17.8 32.3 20.4 wt-% Pitch (524° C.+) yield, wt-% 18.538.5 18.9 37.0 15.3 C₅-524° C. yield, wt-% 62.6 54.9 64.4 61.1 69.4 TIORyield, wt-% 6.1 13.9 5.0 7.3 1.8 Mesophase yield, XRD, wt-% 0.89 0.00*0.41 4.65 1.02 Mesophase, Optical, % 0.12 4.53 6.13 1.35 3.72 *Thisnumber is not trusted. It is believed that the excessive TIOR shieldedthe mesophase from diffraction.

The iron oxide and alumina catalyst demonstrated higher conversion ofpitch, higher C₅-524° C. yield and lower TIOR than comparative catalystsat similar iron contents. Only after extensive pretreatment and high 2wt-% iron loading did limonite come close to rivaling 2 wt-% iron frombauxite after no pretreatment. The pretreated limonite was marginallybetter only in TIOR yield, but had unacceptably high mesophase yield.The bauxite example shows higher pitch conversion, C₅-524° C. yield andlower TIOR yield at 0.7 wt-% Fe than the comparative materials. Thebauxite also out performs hematite which is 97 wt-% Fe₂O₃ suggestingthat the alumina in bauxite provides a performance benefit. Conversiondata from these experiments suggest that the slow formation of ironsulfide in iron sulfate monohydrate and limonite might impede conversionand undesirably increase the TIOR yield.

In many cases in Table IV, the amount of mesophase determined by theoptical method of ASTM D 4616-95 correlates well to the amount ofmesophase determined by XRD.

Example 6

Catalysts from the series of experiments used to generate data reportedin Example 5 in which 0.7 wt-% iron relative to the weight of liquid andcatalyst in the SHC reactor were recovered and examined by XRDspectroscopy and scanning electron microscope (SEM).

FIG. 6 shows an XRD pattern for iron sulfate monohydrate catalyst usedin run 523-4 reported in Example 5. The XRD pattern in FIG. 6 shows asharp peak at 43 two theta degrees identified as iron sulfide indicatingrelatively large crystallite material. The broad peak at 26 two thetadegrees is identified as mesophase. A micrograph of the iron sulfidecrystallites formed from iron sulfate monohydrate precursor crystallitesfrom run 523-4 in FIG. 7 by SEM at 10,000 times indicates a variety ofcrystallite sizes ranging typically from 150 to 800 nm. The iron sulfidecrystallites are the black particles in FIG. 7.

FIG. 8 shows an XRD pattern for the TIOR produced with limonite catalystused in run 522-73 reported in Example 5. The XRD pattern in FIG. 8 alsoshows a sharp peak at 43 two theta degrees identified as iron sulfideindicating relatively large crystallite material. Again, a large, broadpeak at 26 two theta degrees is identified as mesophase. A micrograph ofthe iron sulfide crystallites formed from limonite precursorcrystallites from run 522-73 in FIG. 9 by SEM at 50,000 times indicatesa variety of crystallite sizes ranging typically from 50 to 800 nm. Theiron sulfide crystallites are the black particles in FIG. 9.

FIG. 10 shows an XRD pattern for bauxite catalyst from run 522-125reported in Example 5. The XRD pattern shows a broad, squat peak at 43two theta degrees identified as iron sulfide. This broad peak shape isindicative of nano-crystalline material. No peak at 26 two theta degreescan be identified as mesophase. The peak at 25.5 two theta degrees islikely titania present in the bauxite and/or silver which is suspectedto be a contaminant from a gasket on the equipment. The peak at 26.5 twotheta degrees is also likely a silver chloride contaminant. The peak at28 two theta degrees is boehmite in the catalyst. Because bauxite alsocontains a considerable amount of boehmite alumina in addition to iron,the crystallite size of the iron sulfide was indeterminate from the SEM.

A micrograph of bauxite catalyst used in the run 522-82 reported inExample 5 is shown in FIG. 1. The micrograph in FIG. 11 was made byscanning transmission electron microscopy (STEM) compositional x-raymapping. The micrograph indicates that the boehmite particles range insize from 70 to 300 mm while the iron sulfide crystallites rangeuniformly at about 25 um between about 15 and about 40 nm. The ironsulfide crystallites are the darker materials in FIG. 11 and several areencircled as examples. Many of the iron sulfide crystallites areidentified as single crystallites in FIG. 1. The alumina particles arethe larger, lighter gray materials in FIG. 11. The dark black materialin the top center of FIG. 11 is believed to be an impurity.

Little or no mesophase was indicated for the iron oxide and aluminacatalyst by XRD while the other catalysts formed significant amounts ofmesophase when 0.7 wt-% iron content was present in the SHC reactionzone.

Example 7

TIOR from the series of experiments used to generate the data in Example5 in which 0.7 wt-% iron relative to the weight of liquid and catalystin the SHC reactor were recovered and examined by polarized lightmicroscopy (PLM) using ASTM D 4616-95 to confirm the indications ofmesophase in Examples 5 and 6.

FIG. 12 is a PLM photograph of TIOR produced from run 523-4 with ironsulfate monohydrate catalyst reported in Example 5 and for whichcatalyst an XRD pattern is given in FIG. 6 and a SEM micrograph is givenin FIG. 7 in Example 6. The photograph in FIG. 12 shows a significantamount of material coalesced together indicating mesophase. The PLMphotograph in FIG. 12 supports results from XRD analysis that mesophasewas present by the existence of the peak at 26 two theta degrees and theamount of optical mesophase calculated by ASTM D 4616-95 of 1.7% and byXRD of 1.03 wt-%.

FIG. 13 is a PLM photograph of TIOR from run 522-73 with limonitecatalyst reported in Example 5 and for which an XRD pattern is given inFIG. 8 and a SEM micrograph is shown in FIG. 9. The photograph in FIG.13 shows less material coalesced together than in FIG. 12, but thebubble-like formations indicate mesophase. The PLM photograph in FIG. 13supports results from XRD analysis that mesophase was present by theexistence of the peak at 26 two theta degrees in FIG. 8 and the amountof optical mesophase calculated by ASTM D 4616-95 of 4.65% and by XRD of1.35 wt-%.

FIG. 14 is a PLM photograph of TIOR from run 522-125 produced withbauxite catalyst reported in Example 5 and for which an XRD pattern isgiven in FIG. 1. The micrograph in FIG. 14 shows much less coalescingmaterial than in FIGS. 12 and 13. Only trace amounts of mesophase arepresent in the PLM micrograph supporting results from XRD analysis thatsubstantially no mesophase was present by the existence of the peak at26 two theta degrees and the amount of mesophase calculated by ASTM D4616-95 of 0.00 and by XRD of 0.03 wt-%.

Example 8

A bauxite catalyst containing alumina and iron oxide used in run 522-124reported in Example 5 was compared to iron oxide without alumina, ironoxide with boehmite alumina, iron sulfate, limonite and iron sulfatewith boehmite alumina using the feed of Example 1. Reaction conditionsincluded a semi-continuous reactor at 445° C., pressure of 2000 psi(137.9 bar), a residence time of 80 minutes and iron on catalyst in thereaction zone per hydrocarbon and catalyst of 0.7 wt-%. Results areshown in Table IV.

TABLE V Catalyst Fe₂O₃ + Fe(SO₄) + Bauxite Fe₂O₃ Boehmite Fe(SO₄)Boehmite Run 522-124 522-116 522-109 522-114 522-111 Aluminum content,1.2 0 1.2 0 1.2 wt % Conversion, wt-% 83.1 81.1 79.9 78.1 81.2 C5 to525° C. yield, 69.0 67.3 62.6 63.1 65.2 wt-% TIOR yield, wt-% 2.3 4.95.1 7.2 3.7 Mesophase yield, 0.07 0.60 0.35 0.95 0.36 XRD, wt-%

In each case and for all parameters, addition of the alumina reducesmesophase generation of the iron containing catalyst. Addition ofboehmite alumina improves the performance of iron sulfate in allcategories, but does not appear to help iron oxide except in mesophasereduction. Bauxite has the best performance in each category.

Example 9

The iron oxide and alumina catalyst of the present invention was alsotested for the ability to increase the flowability of heavy hydrocarbonas measured by API index. Heavy vacuum bottoms feed of Example 1 havingan API index of −0.7 degrees was fed to the reactor described in Example4 under similar conditions without any pretreatment of the catalyst. Thecatalyst comprised 3.7 wt-% of the non-gaseous material in the reactor.Iron comprised 17.7 wt-% of the catalyst, so that 0.7 wt-% of thehydrocarbon and catalyst in the reactor comprised iron. The meanparticle diameter of the bauxite was between 1 and 5 microns with a BETsurface area of 159 m²/g. Differing conditions and results are providedin Table VI.

TABLE VI Example 1 2 Pressure 2000 1500 Temperature, ° C. 455 460Reaction time, minutes 80 80 Liquid selectivity, wt-% 81.9 81.0 Cokeyield, wt-% of feed 1.7 0.6 Gas selectivity, wt-% 16.4 18.9 API ofLiquid Product 24.0 23.8 % Increase in API 2470 2450

Table VI shows that the iron and alumina containing catalyst provides anuplift in flowability in terms of API gravity of about 24 times.

Example 10

The alumina and iron containing catalysts were tested with varying watercontents to determine the effect of water on performance on the samebauxite catalyst. The conditions of 455° C., 2000 psi (137.9 bar), asemi-continuous reactor with 6.5 s/min of hydrogen and residence time of80 minutes were constant for all the experiments. Iron content ofcatalyst per non-gas material in the SHC reactor was also constant at0.7 wt-%. The bauxite catalyst tested comprised 39.3 wt-% alumina, 15.4wt-% iron oxide and a loss on ignition (LOI) at 900° C. of 38.4 wt-%which predominantly represents water, had a BET surface area of 235 m²/gand a mean particle diameter of 299 microns. Water content on catalystindicated by loss on ignition (LOI) at 900° C. was varied as shown inTable V by drying. Throughout the experiments, the catalyst comprised63.8 wt-% alumina and 25.0 wt-% iron oxide on a non-volatile basis.

TABLE VII Sample 523-87 523-93 523-94 LOI, wt-% 38.4 23.3 10.6 Pitchconversion, wt-% 84.42 84.31 84.25 C1-C4 yield, wt-% feed 10.78 10.5610.63 C5 to 525° C. yield, wt-% feed 67.70 67.07 68.80 TIOR yield, wt-%3.19 3.33 3.16 Mesophase yield, XRD, wt-% 0.18 0.18 0.18

Performance of the alumina and iron oxide catalyst is comparable at allwater contents. This performance indicates that water content does notimpede the formation of iron sulfide from iron oxide.

Example 11

The alumina and iron containing catalysts were tested at varying largerparticle diameters to assess the effect on performance for similarbauxite catalyst. The conditions of 455° C., 2000 psi (137.9 bar), asemi-continuous reactor with 6.5 s/min of hydrogen and residence time of80 minutes were constant for all the experiments. Iron content ofcatalyst in the SHC reactor was also constant at 0.7 wt-%. The meanparticle diameter was determined using dry and wet methods with ASTMUOP856-07 by light scattering with a Microtrac S 3500 instrument. In thewet method, the weighed sample is slurried in a known amount of waterand sonicated. An aliquot is put in the sample chamber for the lightscattering measurement. In the dry method, a different sample holder isused and the particles are measured directly but also by lightscattering. We believe the dry method gives diameters that more closelyreplicate the character of the catalyst that initially encounters thehydrocarbon feed. Mean particle diameter and performance comparisons arepresented in Table VIII.

TABLE VIII Sample 523-77 523-83 523-84 523-88 523-89 523-87 523-90523-100 Dry mean particle 4.9 4.9 4.9 249 258 299 481 554 diameter,microns Dry median 3.2 3.2 3.2 276 283 327 365 354 particle diameter,microns Wet mean particle 1.0 1.0 1.0 3.3 3.2 4.2 3.5 4.2 diameter,microns Wet median 1.2 1.2 1.2 2.6 2.7 2.9 2.7 3.3 particle diameter,microns Al₂O₃, wt-% 62.2 62.2 62.2 40.2 39.3 39.3 39.5 38.4 Fe₂O₃, wt-%25.3 25.3 25.3 15.9 16.0 15.4 16.0 16.6 BET surface area 159 159 159 246237 235 237 235 m²/g LOI 7.6 7.6 7.6 37.5 36.9 38.4 36.1 38.3 Pitchconversion, 84.6 84.2 85.1 83.7 82.9 84.4 84.8 86.6 wt-% H₂S, CO & CO₂4.2 4.4 4.3 4.2 4.2 4.2 4.3 3.1 yield, wt-% C₁-C₄ yield, wt-% 10.4 10.910.6 10.6 10.5 10.8 10.9 7.9 Naphtha (C₅- 27.2 27.3 28.2 26.9 24.9 26.626.1 26.6 204° C.) yield, wt-% LVGO (204° C.-343° C.) 24.8 24.3 24.425.2 24.1 24.5 25.2 26.1 yield, wt-% HVGO (343° C.-524° C.) 17.7 16.617.0 15.2 16.3 16.5 17.2 17.9 yield, wt-% Pitch (524° C.+) 13.9 14.113.5 14.5 15.2 13.9 13.6 11.9 yield, wt-% C₅-524° C. yield, 70.0 68.369.9 67.3 65.4 67.6 68.5 70.6 wt-% TIOR yield, wt-% 3.7 3.9 3.1 2.7 4.03.2 2.7 2.9 Mesophase yield, 0.12 0.14 0.18 0.06 0.06 0.18 0.07 0.09XRD, wt-%

The alumina and iron oxide catalysts with mean particle diameters over200 microns perform as well as the catalyst with mean particle diametersbelow 5 microns. Comparable performance was observed at mean particlediameters as high as 554 microns. We do not believe that water contentaffected performance comparisons because of our findings that watercontent does not substantially affect performance. Wet method particledeterminations were dramatically smaller which may indicate that themethod breaks the catalyst particles down to finer particles. Thisphenomenon may occur in the SHC reactor.

Example 12

Samples of bauxite with different particles sizes from Examples 10 and11 were subjected to SHC at the same conditions as in Example 5 exceptat reactor temperatures of 455° C. The reactor temperature was 445° C.for iron sulfate. XRD was used to determine iron sulfide crystallitemean diameter based on the width of the iron sulfide peaks at 43 twotheta degrees. Crystallite size was determined using the Debye-Scherrerformula for size broadening of diffraction peaks. Crystallite size andmesophase yield fraction are shown in Table IX.

TABLE IX 523- 523- 523- 523- 523- 523-104 Sample 77 83 88 523-100 89523-87 93 (FeSO₄₎ FeS crystallite mean 10 11.5 11.5 12 12 11.5 9 26diameter, nm Mesophase yield 0.12 0.14 0.06 0.09 0.06 0.18 0.18 0.79fraction, XRD, wt-%

The iron sulfide mean crystallite diameters from XRD for bauxite residein a narrow nanometer range much lower than the smallest iron sulfidemean crystallite diameter for iron sulfate. After recycling the catalystsamples to the SHC once and twice, the iron sulfide crystallite sizesdid not change substantially.

1. A process for converting heavy hydrocarbon feed into lighterhydrocarbon products comprising: mixing said heavy hydrocarbon liquidfeed with hydrogen and catalyst particles comprising 2 to 45 wt-% ironoxide and 20 to 98 wt-% alumina to form a heavy hydrocarbon slurry on anon-volatile basis; heating the slurry to a temperature of at least 410°C. in the presence of sulfur; converting essentially all of said ironoxide in the hydrocarbon slurry to iron sulfide upon reaching saidtemperature of no more than 410° C.; hydrocracking hydrocarbons in saidheavy hydrocarbon slurry in the presence of hydrogen and iron sulfide ina hydrocracking reactor to produce a hydrocracked slurry productcomprising lighter hydrocarbon products; and withdrawing saidhydrocracked slurry product from said hydrocracking reactor.
 2. Theprocess of claim 1 wherein the catalyst particles comprise bauxite. 3.The process of claim 1 wherein the catalyst additionally includes about1 to about 40 wt-% water.
 4. The process of claim 1 wherein thehydrocracked slurry product comprises substantially no mesophase asdetermined by XRD.
 5. The process of claim 1 wherein, said lighterhydrocarbon products having an API gravity of 4 times that of the heavyhydrocarbon feed.
 6. The process of claim 1 wherein more than about 80wt-% of pitch material boiling above 524° C. in the heavy hydrocarbonliquid feed is converted to product having a boiling point temperatureof no more than 524° C.
 7. The process of claim 1 wherein all the sulfurpresent is provided by the heavy hydrocarbon liquid feed.
 8. The processof claim 1 wherein the iron oxide reacts with sulfur provided by theheavy hydrocarbon liquid feed to form iron sulfide.
 9. The process ofclaim 1 wherein the yield of product boiling in the range of C₅ to 524°C. is greater than about 67 wt-%.
 10. The process of claim 1 wherein theyield of TIOR in the product is no more than about 3.0 wt-% of theproduct.
 11. A process for converting heavy hydrocarbon feed intolighter hydrocarbon products comprising: mixing said heavy hydrocarbonliquid feed with hydrogen and catalyst particles comprising 2 to 45 wt-%iron in a +3 oxidation state to form a heavy hydrocarbon slurry; heatingthe slurry to a temperature of at least 410° C. in the presence ofsulfur; converting essentially all of said iron in said hydrocarbonslurry to iron sulfide upon reaching said temperature of no more than410° C.; hydrocracking hydrocarbons in said heavy hydrocarbon slurry inthe presence of hydrogen and iron sulfide in a hydrocracking reactor toproduce a hydrocracked slurry product comprising lighter hydrocarbonproducts; and withdrawing said hydrocracked slurry product from saidhydrocracking reactor.
 12. The process of claim 11 wherein the catalystparticles comprise bauxite.
 13. The process of claim 11 wherein thecatalyst additionally includes about 1 to about 40 wt-% water.
 14. Theprocess of claim 11 wherein the hydrocracked slurry product comprisessubstantially no mesophase as determined by XRD.
 15. The process ofclaim 11 wherein, said lighter hydrocarbon products having an APIgravity of 4 times that of the heavy hydrocarbon feed.
 16. The processof claim 11 wherein more than about 80 wt-% of pitch material boilingabove 524° C. in the heavy hydrocarbon liquid feed is converted toproduct having a boiling point temperature of no more than 524° C. 17.The process of claim 11 wherein all the sulfur present is provided bythe heavy hydrocarbon liquid feed.
 18. A process for converting heavyhydrocarbon feed into lighter hydrocarbon products comprising: mixingsaid heavy hydrocarbon liquid feed with catalyst particles, and hydrogento form a heavy hydrocarbon slurry, said catalyst particles comprising 2to 45 wt-% iron oxide and 20 to 98 wt-% alumina; hydrocrackinghydrocarbons in said heavy hydrocarbon slurry in the presence ofhydrogen, catalyst particles and 0 to 1 wt-% sulfur relative to the feedand catalyst particles in a hydrocracking reactor to produce ahydrocracked slurry product comprising lighter hydrocarbon products,said lighter hydrocarbon products having an API gravity of 4 times thatof the heavy hydrocarbon feed; and withdrawing said hydrocracked slurryproduct from said hydrocracking reactor.
 19. The process of claim 18wherein the hydrocracked slurry product comprises substantially nomesophase as determined by XRD.
 20. The process of claim 18 wherein thecatalyst additionally includes about 1 to about 40 wt-% water.